Stunting, or chronic undernutrition, affects 160 million pre-school children around the world, and imposes significant costs on a child’s health, cognitive development, schooling and economic performance. Most stunting materializes in a very specific age range of 6-23 months when, among other things, children are first introduced to solid foods. But while stunting in this period has been closely linked to generic indicators of dietary diversity, biological studies increasingly link child growth and development to intake of high quality animal-sourced foods (ASFs) rich in protein and other growth-stimulating nutrients. Surprisingly, however, very little experimental research has assessed the impact of ASF consumption on child growth, or explored why ASF consumption is low but also high variable in developing countries. In this paper we redress these knowledge gaps through an analysis of 112,887 children aged 6-23 months from 46 countries. We first document distinctive patterns of ASF consumption among children in different regions, notably the varying importance of dairy and fish in different parts of Africa and Asia, and generally low levels of meat and egg consumption in these regions. We then test how ASF consumption affects child stunting in multivariate models saturated with control variables. We find strong associations with a generic ASF consumption indicator as well as with fish and dairy consumption. Finally, we explore why ASF consumption is low but also so variable across countries and regions. We show that non-tradable ASFs (fresh milk, eggs) are a very expensive source of calories in low income countries, and that caloric prices of these foods are strongly associated with consumption patterns. A host of other demand-side factors are also important, but the strong influence of prices implies an important role for agricultural policies – in production, marketing and trade – to improve the accessibility and affordability of ASFs in poorer countries.